BEIRUT, Lebanon – A powerful car bomb that killed a Christian lawmaker from the governing coalition and six others was the latest in a deadly string of attacks that have rocked Lebanon’s teetering political order as the country prepares to select a new president.

The bombing Wednesday appeared to have deep political implications, giving credence to longstanding fears of a plot to eliminate the razor-thin majority in Parliament of the governing March 14 movement.

The bomb, apparently hidden inside a parked car in the Sin el Fil neighborhood, exploded just as Antoine Ghanem of the Christian Phalange Party, drove past. The explosion ripped through the busy street, crushing cars and damaging buildings nearby.

Ghanem, 64, and his bodyguard died instantly, security officials said, and five passers-by were also killed. At least 19 others were wounded, medical workers and security officials said.

“It went dark, then a blinding light followed,” said Toufic Shabib, who owns a flower shop near bombing site. “I ran outside, everything was burning, cars, people. It was like a war zone.”

The blast raised concerns that Lebanon’s political turmoil may be taking a turn for the worse as parliament prepares to meet next week for the first time in almost a year for one of its most significant tests: choosing a new president to replace Emile Lahoud, who must step down on Nov. 25.

Lebanon has been locked in a 10-month political stalemate between the pro-Western government of Prime Minister Fouad Siniora and the Hezbollah-led opposition, backed by Iran and Syria. The opposition, in part trading on Hezbollah’s popularity after its war with Israel a year ago, has been demanding a greater role in government.

And the country has faced one security threat after another, with seven car bombings in the capital this summer while the army battled Qaida-inspired militants in a Palestinian refugee camp in northern Lebanon.

In Washington, the White House condemned the attack and strongly suggested that Syria was behind it, though the press secretary, Dana M. Perino, stopped short of accusing Syria outright. “There has been a pattern of political assassinations and attempted assassinations designed to intimidate those working courageously toward a sovereign and democratic Lebanon,” Perino said. “The victims of these cowardly attacks have consistently been those who publicly sought to end Syria’s interference in Lebanon’s internal affairs.”

It was not immediately clear how the assassination would affect the political process or the March 14 movement’s narrowing majority in parliament.

Ghanem was the fourth anti-Syrian lawmaker and the eighth leader assassinated since a massive blast killed former Prime Minister Rafik Hariri in 2005, setting off a cycle of political crises. A number of lawmakers, apparently nervous about the situation, have been outside of the country in recent weeks. Ghanem had been away and had returned only two days before.

With Ghanem’s death, March 14 will control 67 out of the 128 seats in Parliament; to elect a president outright, it must have a simple majority of 65.

“What is clear is that there is someone working on depriving the majority of its majority,” said Ziad Baroud, an independent Lebanese lawyer. It was unlikely that an election to replace Ghanem could be held before next week’s expected parliamentary session.

“These assassinations are connected to the presidential election,” he said.

Last November, Pierre Gemayel, a member of parliament with the March 14 movement, was assassinated by gunmen in a busy street; in June, Walid Eido, a Sunni Muslim member and outspoken critic of Syria, was killed in a bombing. March 14 members blame Syria for the killings.

In a major blow in Aufgust, an opposition candidate, Kamil Khoury, defeated former President Amin Gemayel, the father of Pierre, in a pivotal election to fill Gemayel’s vacant seat.

Khoury is allied with a Christian rival of the governing coalition, former Gen. Michel Aoun, who has, in turn, made common cause with the opposition Shiite Muslim Hezbollah Party and has led a single-minded quest to become president.

In Damascus, a statement by a “media source,” quoted by the official news agency, SANA, condemned the assassination on Wednesday as an act that “targets the efforts and endeavors exerted by Syria and others to achieve the Lebanese national accord.”

Mahdi Dakhalallah, Syria’s former information minister, said in a telephone interview, “This could be destabilizing for Lebanon, Syria and the whole region.” He added: “I hope this event will be more reason for Lebanese to go and vote to elect a new president for national unity.”